Rustic Onion Gratinée
By Emma
Certified Culinary Professional
•
Recipe tested & approved
A rich, smoky onion soup with a twist of sherry that deepens flavors. Caramelized sweet yellow onions replace reds for mellower notes. Chicken stock in place of beef broth cuts heaviness but keeps umami intact. Parmesan joins gruyère for sharper melt and golden crust. Bread cast in olive oil instead of grilled—more rustic, more crunch. Slightly longer caramelization lets sugars bloom, pushing beyond shallow sautéing. Broil step focused on crisp cheese and toasted bread with bubbling edges. Thyme swapped for rosemary for piney aroma. Wine reduced carefully till thickened—no harsh alcohol burn. Breaks standard rules but rewards patient noses and eyes. Keep butter modest here; too much dulls sweetness.
Prep:
22 min
Cook:
30 min
Total:
52 min
Servings:
4 servings
#French cuisine
#onion soup
#caramelization
#cheese gratin
#rosemary
#sherry
#bread toast
Ongoing onion caramel. Patience over heat, the slow magic. Past attempts with reds ended sharp, almost biting. Cut back butter, coax onions to sweet gloss gradually. Switched broths mid-trial; beef was too heavy, masked nuances. The surprise was sherry, barely present but shifts the whole flavor. Rosemary instead of thyme—pine notes playing against sweet onions. Bread deserves respect—charred early, soggy ruins the point. Olive oil brushing gave crunch without greasiness. Cheese mix nailed that molten & browning balance; too much Gruyère yielded stringy mess. This version is layered. Aromatic, inviting, and rustic. Bread soaks just right beneath crust. Mastering broiler timing here means difference between caramelized cheese veil and burnt sacrifice.
Ingredients
- 4 large yellow onions thinly sliced
- 30 g butter
- 750 ml chicken stock
- 400 ml dry sherry
- 3 ml dried rosemary crushed
- 4 thick slices crusty country bread
- 180 g grated gruyère and parmesan mix
- Olive oil for bread brushing
- Salt and freshly cracked black pepper to taste
About the ingredients
Yellow onions instead of red soften acidity, promoting sweeter caramelization. Butter kept moderate to avoid greasy heaviness and let natural sugars pop. Chicken stock chosen over beef for lighter body, allowing wine and herbs room to shine. Replaced red wine with dry sherry to soften harsh edges—a subtle flavor shift but noticeable. Rosemary instead of thyme for a piney aromatic note, playing with the sherry well. Brushed bread with olive oil, not butter; less heavy, crisper base under cheese. Cheese blend uses Parmesan alongside Gruyère to add sharpness, balancing meltability with a nutty crust. Salt and pepper adjusted late to safeguard against over seasoning due to reduced broth volume on simmer.
Method
- 1. Start with a heavy-bottomed pot over medium-low heat. Melt butter — not too hot or it browns too fast. Toss in onions. Slow cook, stirring every 5 min. Your goal? Soft gold, edges caramelizing, rich onion smell flooding kitchen. 25-30 min can’t rush it. Patience here wins you layers.
- 2. While onions do their thing, pour sherry into a small pan. Bring to gentle boil, reduce by half. Watch close — this thickens and concentrates, no alcohol bite left. Set aside once syrupy, dark amber color. This trick tightens taste without literal booze punch.
- 3. Add rosemary, salt, pepper straight to onions. Splash in chicken stock, swirl to lift fond stuck on pot bottom. Let this simmer now, uncovered, 10-12 min. Broth reduces slightly, onions soften fully, rosemary scent wakes up the mix. Taste to confirm balance—adjust salt or herb.
- 4. Meanwhile, brush bread slices with olive oil instead of butter or raw grilling. Place on baking tray, toast in oven at 180°C for 6-8 min until crisp and golden but not burnt. This adds dry crunch contrast—important when submerged later.
- 5. Preheat broiler/grill on high. Assemble: ladle soup into ovenproof bowls. Lay oil-toasted bread thick and evenly on top. Pile on cheese generously—a 60-40 blend gruyère to Parmesan makes cheese crust nutty with gooey pull. More Parmesan means more bite, less stringiness. Your call.
- 6. Place bowls under broiler. Watch CLOSELY. Cheese bubbles, edges brown, toast darkens slightly—this takes 4-6 min. Don’t wander or lower rack distance, or cheese dries out or burns. You want molten with crunchy peaks.
- 7. Remove, rest 2 min. Soup cools just slightly, flavors marry—cheese softens further but still holds crust. Serve with heavy napkin. Spoon hits bread then velvety broth beneath. Crunch then melt. Onion sweetness with woody rosemary background. Sherry note lingers last.
- Notes: Use yellow onions here for subdued caramel, red ones overpower unless you want sharper tang. Sherry tames dark wine’s acidity, offers mellow warmth. Rosemary replaces thyme: piney instead of floral, matches sherry better. Olive oil on bread keeps crust crisp longer, prevents sog. Chicken stock lighter than beef but keeps deep flavor if you toast onions well—burnt onion ruins whole pot. Adjust salt last; butter content low so flavor shines through.
Cooking tips
Caramelizing onions is where timing gets relaxed but tactile cues are critical—look for deep golden edges, sweet smell wafting; no rush, no high heat. The sherry reduction cooks off alcohol, leaving robustness without biting taste—visual deepening to syrup-like consistency is the sign. Adding herbs and simmering lifts flavor bonds; skim if foam appears. Toasting bread with olive oil provides a dry crisp counterpoint to the soup’s softness. Broiler step is unforgiving, watch for bubbling cheese and edges to brown evenly. Left too long, cheese crisp hardens or burns; too short, cheese won’t brown or melt properly. Resting helps flavors marry and temp becomes spoon-friendly. Butter quantity controls richness; too much and soup turns greasy, masking sweet onion base. Spot seasoning last with tasting. Avoid cheap cheese—texture and melt quality vary tremendously. Using ovenproof bowls or crocks critical for safe broiling.
Chef's notes
- 💡 Slow caramelize yellow onions low heat. Listen for gentle sizzle not a roar. No rush—sugar blooms deep gold, edges crisp slightly. Too hot burns bitter. Stir every 5 min. Texture shifts from raw to soft silk. Patience pays here—flavor grows inside layers.
- 💡 Sherry reduction thickened dark amber means alcohol cooked off but taste stays rich. Watch closely or scorched bitterness kicks in. Half reduction approx. Start cold pan, bring to gentle boil then lower. Set aside paused dark syrupy bubble, big flavor boost without booze punch.
- 💡 Brush country bread slices with olive oil not butter. Adds dry crisp crunch after baking. Avoid sog soft bread under cheese puddle. Toast in moderate oven around 180°C 6-8 min edges brown lightly. Oil creates barrier seal while toasting, keeps crumb firm yet slightly yielding.
- 💡 Cheese blend crucial—60 gruyère to 40 Parmesan. Gruyère melts oozy stringy but mild. Parmesan sharp, crunchy crust, nutty bites. More parmesan equals brittle crust but intense chew. Too much Gruyère can cause stringy mess. Adjust ratio to texture preference with mind on browning behavior.
- 💡 Broiler step unforgiving. Cheese bubbles quickly, melts then browns. Eyes on bowl. 4-6 min max. Too close lowers rack risk burning, too far gives limp cheese. Watch for foaming, edges darken to golden brown peaks. Resting 2 min finishes melt internally and tames heat. Timing critical.
Common questions
Can I use red onions instead?
Red onions harsh sharp. Overpower sweetness. They caramelize but tang dominates. Use yellow for mellow, layered sweet. If desperate toss in but watch bitterness climb fast. More butter helps soften red but risky for greasy finish.
What if no chicken stock?
Substitute vegetable broth or water with bouillon cube diluted. Chicken lends lighter body versus beef which can mask nuances. Without stock flavor less deep but sherry and onions still carry main notes. Adjust salt carefully when switching liquid base.
Why does my cheese burn under broiler?
Common issue. Too close heat or too long exposure dries out oils. Cheese scorches fast with broiler intense direct flame. Use timer, keep eye forward, rack positioned mid or top third. Watch bubbling edges color shift golden from pale white.
How to store leftovers?
Refrigerate sealed container max 2 days. Cheese crust loses crunch but overall flavor holds. Reheat oven slow 150°C to regain some texture, avoid microwave melting cheese into rubbery blob. Soup thickens when cold—thin with splash broth if needed.
